1. Field of the Invention
The present invention relates to a backlight module, and more particularly, to a backlight module capable of arising heat dissipation.
2. Description of the Related Art
A backlight module is a key component of a liquid crystal display (LCD). The purpose of the backlight module is to provide a sufficient-brightness and an even-distribution of light on surface to the LCD panel. Because the LCD is widely used in various electronic products such as monitors for notebook computers, digital cameras, and projectors, the demand for the backlight module has increased tremendously.
In addition to cold cathode fluorescent lamps (CCFLs), light emitting diodes are increasingly used in medium and large size liquid crystal displays. Please refer to FIG. 1, which shows a prior art backlight module 10 having a plurality of light emitting diodes disposed on a bezel. Conventionally, the plurality of LEDs 12 are disposed at the sides of bezel 16 and emit light beams upon receiving driving signals from a driver (not shown) via a pin 18. An arrow A indicates a direction of light axis of the LED 12. A greater power LED emits higher brightness and generates more heat as well. In order to promptly dissipate generated heat, a traditional way is to position the LED 12 on a metal core printed circuit board (MCPCB) 14. The generated heat is rapidly transferred to bezel 16 and is therefore dissipated by means of air convection. In addition, for more efficient heat dissipation, both the metal core printed circuit board (MCPCB) 14 and bezel 16 are made of metal with high thermal conductivity.
With a rapid development of LED manufacturing, maximum luminance provided for new LEDs is greater. Certainly, using new LEDs can reduce the number of LEDs used in a backlight module, thereby reducing the cost. Nevertheless, luminance of the LED is inverse proportion to its operating temperature and thus shortens the life span of the LED, and how to improve the heat dissipation in order to lower operating temperature of the LED is a main goal for backlight module manufacturers.